AbstractThe influence of surface roughness in the amplitude of the ultrasonic signal was evaluated. We used the technique of pulse-echo by direct contact in order to determine the presence of flaw indication.We studied steel AISI/SAE 4340 samples with roughness of 0,5?, 2.0?, 8.0? and 12?. We also, drilled holes of several diameters, witch act as reference reflectors at frequencies of 2.25, 5.0, 7.5 and 10 MHz. Best indications of reflectors were obtained at the frequencies of 5.0 and 7.5 MHz in steel samples.It can be seen, from test result, that the attenuation of the signal depends strongly on the surface roughness. Spectral analysis of signals shows that attenuation increases as the surface roughness.Introduction

AbstractUltrasonic velocity measurements have been carried out in Ni base superalloy Inconel 625 alloy in 1. service exposed, 2. service exposed followed by thermal ageing and 3. resolution annealed followed by thermal ageing conditions.The ultrasonic velocity has been correlated with the precipitation behaviour and yield strength in various heat-treated conditions. The study revealed that different precipitates, such as Ni2(Cr,Mo),?'', ? and grain boundary carbides, affect the yield stress and ultrasonic velocity differently and hence the type of the precipitate plays an important role in the correlation of these two parameters in Inconel 625.Introduction The ultrasonic wave propagation is influenced by the microstructure of the material, through which it propagates. The velocity of the ultrasonic wave depends upon the elastic moduli and the density of the material, which in turn are

Use of data fusion methods to improve reliability of inspection : synthesis of the work done in the frame of a european thematic networkF. Nathalie, K. ValerieSwiss Federal Laboratories for Materials Testing and Research (EMPA)269, Dübendorf, SwitzerlandRadiographic Testing (RT), Ultrasonic Testing (UT)

AbstractIn the frame of the Plant Life Assessment Network (PLAN European Thematic network), a working group has been organised around the theme of "Data Analysis and Fusion". This was a mean to develop scientific exchanges between European projects dealing with similar problems. In this paper, the interest of data fusion is shown through the results of two Brite projects, where one area of innovation was to combine automatically the data coming from two NDT methods (X-ray and ultrasonic techniques). The interest is to deliver a global inspection report on the sample under test, and thus increase reliability. These projects ended respectively in February 2000 and December 1999, and the data fusion was validated.IntroductionIn more and more inspection applications, we need more than one type of measurement to tell us everything we want to know about a component, a process, ... Moreover, even one measurement must be as reliable as possible, and reliability must be quantified. To this end, data fusion is a

IntroductionEddy Current NonDestructive Testing is widely used to inspect conducting materials during manufacture or in service. In this context, modelling is a powerful tool for inspection improvements : it helps probe-coil designers to optimise sensors for each examination requirement, it gives better understanding of the involved physics, it helps operator training and it also increases defect analysis reliability. Moreover, the fast computation speed of these models facilitates greatly the process of the experimental data inversion. The models developed in CIVA/MESSINE, where MESSINE stands for " Models for Electromagnetic Simplified SImulation in Nondestructive Evaluation " are based on simplified (analytical or semi-analytical) fast-running 2D and 3D solutions for the Maxwell equations. With these models among which four are presented in this paper, various kinds of studies can be led in order to optimise the Eddy Current NonDestructive Testing. The axisymmetrical model (figure 1) is particularly adapted to the study of the design of probes and to the evaluation of the thickness of materials. <

Abstract The traditional methods of thermal non destructive control are based on the analysis of the temperature profiles of surface, which are responses to a thermal excitations at the output of the studied system. Generally, these methods require an excitation of form well defined in order to execute the inspection. In this article, we present a method of thermal non- destructive analysis of thermal response of material containing a plan defect in the frequency domain, not necessitating any specific form of the input signal. This method is based on the concept of thermal input impedance, which may describes the dynamic behaviour of any system when the thermal limit conditions are known. The investigations by simulations implemented in this work, in the assumption of one dimensional condition, concern particularly the distribution of the thermal input impedance versus the frequency of excitation signal, and the defect position in the structure in question.Keywords:Diffusivity; Effusivity; Thermal impedance; Temperature; Heat flow; Non- destructive testing<

SummaryThe thermal characterisation of material constitutes an important area of the thermal metrology. In this article we use a new approach of non destructive thermal control to analyse and characterise inclusion defects in flat plates. This approach is based on control volumes and the finite differences method . We have been interested particulary in unidirectional transfers l. The obtained responses allow to establish curves between maxima of heat flow differences (flow with defect - flow without defect) with the position and the thickness defect.1 IntroductionThe main concern of manufacturers of materials, is to know if these materials that contain defects which can deteriorate their rigidity. It is so, the recourse to the non destructive thermal control methods be essential. Indeed non destructive thermal control is a technique which allows the analysis of various structures by the study of their responses to thermal excitations, and the establishment of a relation between this response and the imperfections which they contain [2]. The defects and the structure have different thermophysical properties; the presence of

AbstractAssessment of copper canisters for spent nuclear fuel requires means for detecting and sizing voids as small as 1 mm in diameter, located up to 4 mm under the surface. Eddy current technique for the detection and characterisation of deep voids in copper is presented in the paper. Results were obtained using two deep penetrating probes, the standard MDK 33 from Rohman, and a specially designed probe MDF 1201 from Leotest.The detection ability of the above probes was evaluated and compared using a specially designed sandwich specimen. The specimen was designed to simulate voids with different volumes, located in copper at different depths.Eddy current responses of the two probes were acquired using an automatic scanner for a number of artificial voids with different depths and volumes. The method of defect characterisation (estimating void depth and size) was established. It was shown that the detection of artificial void (cylinder with diameter 1mm and height 1 mm) located at the depth of 4 mm was possible using the probe MDF 1201 at the test frequency of approx. 700Hz. It appeared that defect characterisation was relatively

AbstractGas turbines and particularly their hot path components exhibit relatively high maintenance cost and short in-service inspection cycles, in comparison with most main components of thermal power plants. The overall share of production capacity covered by gas fired combined cycle and CHP plants utilising gas turbines is still increasing, and the short inspection and maintenance cycles suggest corresponding strong growth for NDT services.NDT of gas turbine components is typically specified for three different purposes: within the shop during different phases of manufacturing or repairs, for user acceptance of new or reconditioned components, and for in-service assessment on the run/repair/replace decisions. The most demanding inspections in many ways are those performed in the field, as the available methods and access for the inspections can be fairly limited. Majority of the field inspections apply visual and surface techniques, but also ET and UT appear to find increasing use as they provide the potential advantage of indicating flaw depth. Examples are shown on in-service and ex-service inspections of hot end components, particularly turbine blades and vanes.<

AbstractApparently that the type testing procedure should be conducted under the conditions ensuring reproducibility of its outcomes. We investigated various factors effecting upon the reproducibility. To obtain quantitative characteristics of indication's visibility the image-processing hard-and software were used. It was established that there are two main groups of these factors. The first depends on the differences between various test panels, which are used for type testing. The second one concerns the reproducibility of some stages of penetrant testing procedure (excess penetrant removing and developer application). The recommendations to increase the reproducibility of type testing are developed and illustrated experimentally.The determination of penetrant system sensitivity as a part of type testing should be conducted ensuring reproducibility of the result. We investigated some factors effecting the reproducibility. To obtain quantitative characteristics of indication's visibility, an image processing system was used [1]. We used 3 different sets of reference blocks (rb1, rb2, rb3) corresponding to type 1 of EN ISO 3452-3 [2]. Two fluorescent penetrants with different sensitivities and the same wet solvent developer were used.

SUMMARYResults of investigations performed at specimens prepared by BAM, Berlin, BASt, Bergisch Gladbach and Darmstadt Technical University, which contain partially filled tendon ducts are presented. These specimens differ in the used concrete mixture and in the content of ordinary reinforcement. The measurements were taken utilising the pin contact shear wave ultrasound transducer array A1220 which is manufactured by MSIA Spectrum, Moscow. It is the aim of the investigations to check the capability of the applied technique to find areas of the ducts which are unfilled with grout. Therefore statistical techniques evaluating the amplitude of the back scattered ultrasonic signals are applied. These techniques were developed and tested in former investigations.1. INTRODUCTIONUsing post tensioned simply supported and continuous beams has been the dominating technique of bridge building during the last fifty years. The basic idea is to produce compressive stress within a beam by prestressing cables anchored at both ends of the beam. The cables are guided by ducts which are embedded in the reinforced concrete beam. A bond between the

SUMMARYUltrasonic images of concrete structures contain distorting components besides the desired information on relevant alterations of density and Young's modulus. The subjective interpretation of the operator with respect to these alterations is based on the brightness information and on known morphologic aspects. It is the aim of the research work presented here to allow for an objective interpretation of the brightness distribution using statistical image processing. This is done by determining statistical quantities describing the probability of certain pixel amplitude of the ultrasonic image.In principle it doesn't play a role which type of ultrasound technique is actually used to collect the data and to put the picture together. The basic requirement for a successful application of statistical methods is the availability of a large number of reliable data resp. pixels in the case under consideration. These data are collected in the reflection techniques by scanning the accessible surface. In the following presentation the pictures under discussion had been put together by the Synthetic Aperture Focussing Technique (SAFT) using compressional ultrasound waves. In [1] pictures based on shear wave reflection signals are presented and interpreted making use of the same basic statistical methods. For obvious economical reasons there is

AbstractThe main component of air-driven pumps are elastic diaphragms. These diaphragms are made from rubber or some other flexible material such as a thermoplastic elastomer. A method based on frequency analysis of the acoustic signal obtained from an air-driven pump during operation is described in this paper. A fully digital system for frequency analysis based on a personal computer was developed for practical implementation of this method. The system was tested under laboratory and in plant conditions. Two types of laboratory tests were performed: tests performed on diaphragm containing different types of artificial flaws and tests performed on different types of diaphragm. Three tests were performed under in plant conditions. The main goal of these tests were to demonstrate the ability of the system in early failure detection of the pump. The tests were performed under very high level of background noise and lasted between two days and two weeks in length. During this time the system performed acquisition and data processing at 10 seconds intervals. These tests have demonstrated that our system can indicate impending pump failure at least four hours before actual failure.

AbstractThis paper deals with the investigation of the influence of various external factors (longtime exploitation; friction; corrosion) on Fe alloys water pipes mechanical properties studied by the microindentation method along with acoustic emission one. It has been shown that long-time exploitation (as well as aging) don't practically change such characteristics as hardness and brittleness. The fine polishing has a very small influence, while coarse grinding slightly increases these parameters. The most effect of brittleness increase has been observed for the water pipes subjected to corrosion.IntroductionIt is well known that iron is one of the leading materials in the modern industry. The iron alloys account nearly for 90 % of the total metallic production. Such a large application of these materials is stipulated by their optimal exploitation properties: high values of strength and fracture stability in combination with the reasonably good ductility and flexibility. However the influence of various external factors can lead to the essential and undesirable changing of these properties during

AbstractA combined nondestructive way for identification of minerals which constitute the rocks and for the estimation of their strength and brittleness has been proposed. The method includes the microstructure examination permitting to characterize the separate phases, grains, various impurities, and the microhardness testing in combination with the control of brittleness using the registration of acoustic emission signals. Along with the possibility of mineral and rock diagnostics this method can be suitable for the characterization of structural parts of various composite materials: alloys, plastics, ceramics, glasses, etc. IntroductionAt least two reasons stipulate a constantly increasing interest to the study of rocks strength properties. On the one hand, such kind of research improves the understanding of the nature ability to create a lasting materials resistant to super-high pressures, sharp temperature changes, etc. On the other hand, the steady tendency to the industrial use of different rocks in combination with the various materials for the technical and civilian buildings, roads, sanitary equipment and many other applications is observed in the last decade

IntroductionA new and rapid ultrasonic pulse echo technique has been used with great effect to scan the concrete lining of two railway tunnels. The instrument used was the A 1220 from MSIA Spectrum in Russia. Working side by side two engineers from FORCE Technology were able to make a full and detailed survey of the concrete thickness and homogeneity along 1300 m of tunnel, covering an area of over 10,000 square metres in less than two months. This is an example of the advances that have recently been made in non-destructive testing of concrete and demonstrates the capability of modern technology in providing the much needed post construction checks of civil engineering structures.In the Autumn of 2001 the go-ahead was given for completion of the railway tunnel through a major ridge in the south of Sweden. The work began several years ago and has been interrupted by several set-backs. In the northern entrance to the twin tunnel some 1200 m have been completed, of which 650 m have been constructed with an inner 600 mm thick concrete lining cast in-situ. This concrete lining has been cast against a 4 mm plastic

AbstractThere is a large potential of acoustic methods in antipersonnel landmines detection based on materials characterisation. In this paper the resolution capability of one realisation of that principle is described and quantified. Resolution capability is modelled with different requirements imposed. Using appropriate experimental set-up, that quantity is determined in laboratory conditions for a representative, referent set of testing objects. Results obtained in modelling and experimental work show both the usefulness of resolution capability as an indicator of a buried object materials characterisation, and the reached level of buried object materials characterisation using applied approach.IntroductionLarge number of 80 million mines left in more than 80 countries world-wide [1] cannot be efficiently removed using present day humanitarian demining [2, 3]. As a crucial phase in humanitarian demining, which is responsible for a majority of duration and risk, antipersonnel mine detection (APMD) has been recognised [3, 4]. These facts motivated scientists and experts from NDT community and related fields to start research and

AbstractThe reliability investigations are dedicated to throw light on the performance of the NDE system with respect to the required aim. This is especially of interest when it is looked for life damaging objects in the case of mine seeking and when it is even more difficult to distinguish between the different suppliers of methods concerning their actual capability. In accordance with the conception of EFNDT WG5 and CEN BT 126 CW 07 the authors have the aim to transfer the knowledge in reliability measurement of NDE systems to the reliability measurement of mine detection systems. For this the three basic ways to investigate the reliability of NDE signals will be described. The first way of investigation, the performance demonstration, is preferred e.g. in the US American nuclear power industry. This is an integral consideration of the non destructive test as a system where the whole NDE system is packed in a black box and only the input in terms of the real existing flaws in the component is considered and compared to the output in terms of the indications of the human inspector or of the automated system. The second - the European tradition - relies on a standardized description

AbstractThis contribution presents numerical modelling results for typical piezoelectric transducers and non-destructive testing situations. Starting from the transducer modelling of straight-beam and angle-beam probes up to the simulation of the time of flight diffraction (TOFD) technique and the long-long-trans (LLT) technique, results are given as A-scans and time domain snapshots of the ultrasonic wavefield, which provide an excellent way to interpret the pulse signature shown in the A-scan.IntroductionSimulation tools in non-destructive testing with ultrasound deserve more and more attention on behalf of their capability to produce real-life synthetic data; these data are of significant help in the interpretation of recorded A- and/or B-scans. EFIT, the Elastodynamic Finite Integration Technique, starts with the elastodynamic governing equations in integral form. This means that EFIT simulates the nature of ultrasonic waves without any approximations. EFIT discretizes the basic field equations uniquely on a staggered grid; a pertinent code has been implemented

AbstractThe Transmission Line Matrix ( TLM ) is a physical discretization approach used to solve the wave equation numerically. The method replaces a continuous system by a network or an array of lumped elements. The TLM method involves dividing the solution region into a rectangular mesh of the transmission line segments. The nodes of the mesh are the points of discontinuity for acoustic impedances.A computer program based on transmission-line matrix (TLM) model was developed to simulate the ultrasound propagation media with different acoustic impedances. The numerical model provides both frequency and time domain responses. The influence of variations in the shape of the incident pulse is discussed. The numerical results are compared with those obtained from experiments.IntroductionTo improve the results obtained in ultrasonic NDT , considerable theoretical effort is involved in developing reliable mathematical models of wave propagation in different media. Due to the complexity of the problems, numerical methods have proven to be an appropriate approach. Among other

AbstractUltrasonic non-destructive testing of components made of austenitic steel is complicated by a structural noise and shape of cracks. For improvement of detection and characterisation of such cracks the ultrasonic synthesised aperture focussing technique (SAFT) may be applied, however efficiency of the SAFT depends on accuracy of the input parameters. In order to optimise the processing algorithms and to estimate the potential possibilities of various NDT methods, the numerical model has been developed. The model enables simulate propagation of ultrasonic waves in materials possessing a granular structure. For computer simulation of granular materials a novel method based on application of Voronoi diagrams was developed. For simulation of cracks fractal theory was applied. Propagation of ultrasonic waves in granular medium was simulated using the ray tracing approach. The performance of the proposed model is illustrated both by the simulated and experimental data. IntroductionDevelopment of cracks in austenitic steel induced by intergranular stress corrosion is essential factor reducing reliability of pipes used in nuclear power plants. Propagation of ultrasonic waves in such materials is accompanied by strong